Recovery of phenols from ammoniacal liquor



Dec. 2.2A 1.925. 1,566,796

LE ROY W. HEFFNER ET AL RECOVERY 0F PRRNOLSv FROM AMMONIACAL LIQUOR Filed Dec. 16, 1924 3 Sheets-Sheet 2 Nvwhl kaum@ DBMLIE Patented' Dec. 22 192.5.

' UNITED* STATES LE ROY WILBURHEFFNER, OF EAST NORRIS'I'OYVN` TOWNSHIP, MONTGOMERY COUNTY,

1,666,196 PATENT oFFicE.

AND WILLIAM TIDDY, 0F. JEFEERSONVILLE, PENNSYLVANIA.

RECOVERY 0F PHENOLS FROM AMMONIACAL LIQUOB.

Application inea December 16, 1924. seriai no. 756,194.

from Ammoniacal Liquor; and'we do herebyA declare the following to be a full, clear, and exact description of the invention, such as will enable 'others skilled in the art to` which' it appertains to make and use the saine.

This invention relates to the recovery of phenols from ammoniacal gas liquor, ctc.

Gas liquor from coke ovens and gas works contains a considerable amount of ammonia together with varying percentages of phe- `nols and phenolic bodies. The phenols may, for example, amount to as much as 4 grams per liter or more While the ammonia runs up to 14 or more grams per liter. According to the usual procedures, the ammonia 1s removed from the gas liquor in ammonia stills and is recovered in absorbers as ammonium sulfate or in the form of a concentrated solution of ammonia known as aqua-ammonia or concentrated liquor. Phenols arel for the D most part retained in the waste liquor coining from the ammonia still and are lost.

In the-usual. process of treating gas liquor the liquor is introduced cold into the top o the ammonia. still, so that the upper portion of the still contains liquor at a temperature considerably below the boiling point of water. In aqua-ammonia plants and in plants manufacturing concentrated ammonia, the liquor'is first preheated to drive of carbon dioxide and hydrogen sulfide, before introducing it into the ammonia still, and the still has a reflux condenser or dephlegmator, maintained below the boiling point of water, to condense excess water vapor from the gases. l.The liquor passing down through the free ammonia still loses most of its free ammonia content and passes into the lower part of the still where it comes into Contact with lime in what is known as the lime leg. The -lime sets` free any ammonia which is present in acombined form and the liquor then lpafses to a second still known as the A fixed ain'inonia still which volatilizes the ammonia from the liquor and causes the voli atilized giminoiiia to Vpass upwardly through the free ammonia still. The waste liquor is drawn olf from the bottom of the fixed still and is usually allowed togo to waste. Due to its phenol content it cannotV be discharged into bodies of Water which are to be the source of drinking water, particularly where the water is subjected to chlorination. The

Vammonia fromA the ammonia still, in the case of aqua-ammonia manufacture, passes through a deplilegmatoi', a water and an alkali Washer and then through charcoal and bone-black filters and is finally absorbed in distilled water, producing the aqua-ammo-- nia solution of commerce, For the manufacture of ammonium sulfate, the ammonia "gas is passed through a saturator containing sulfuric acid.

It is one of the objects of the present invention to recover from gas liquor a substantial proportion or all of the phenols which have heretofore been permitted to go to waste, and, at the same time, to recover the ammonia from the gas liquor.

According to the present. invention, instead of introducing cold liquor into the still, or, when the liquor is preheated, instead of running the free ammonia still with a reflux condenser or, dephlegmator at a relatively low temperature and refluxing most of the condensible ingredients from the vapors, the liquor in the still head is kept at a relatively high temperature, above 98 C., and a phenol absorber is inserted between the still and the ammonia condenser in order to remove phenolic compounds from the gases. The percentage of phenol which is recovered in the present process depends on the teinperature of the escaping vapors and of the liquor in the top of the free ammonia still, and on the ratio between the ammonia and phenol present in the gas liquor in the still. In general, the greater the proportion of ammonia to phenol the greater will be the percentage of phenol removal from the gas l1quor, up to the oint where all the phenol .is removed.l If esired, additional ammonia may be added to the gas liquor or .may be introduced into the still in order'to increase the recovery of phenol and effect substantially complete recovery.

The improved process of the present 1nvention, in its broader aspects, can be carried out in ammonia stills such' as are now commonly used in the art, provided they are so constructed or designed. that both the va,-

pors and liquor in the top of the free ammonia still can be maintained' at a temperature above 98 C., e. g. between 98 and 103 C. Where such free ammonia stills are provided with a reflux condenser or dephlegmator, .this should be removed, or provision should be made for heating it so as to maintain a sulliciently high outlet temperature, i. e. 98 C. or higher. In addition, the invention includes a recovery system for purifying the ammonia from its admixed phenolic compounds and for recoverlng the phenols.

The phenol recovery system, in 1ts general aspect, may `be similar to the phenolic recovery systems now used for absorbing and recovering phenols from other sources. For example, the admixed ammonia and phenolic compounds, in vapor form, and admixed with a relatively large amount of Water vapor, may be passed through a suitf able phenol absorber, such as an alkali Washer in which the phenolic compounds are combined with the alkali as alkali phenolate. Owing to the high temperature at Which the gases escape from the ammonia` still, they may contain a relatively large content of steam or Water vapor uhich tends to condense in and to dilute the alkali liquor used for combining with the phenol if the liquor in the washer is at a lower temperature than the vapors. We find this can be prevented by maintaining the alkali solution at a sufficiently high temperature to drive oliI the Water vapor and maintain the alkali solution in a relatively concentrated state. When this is done, the ammonia vapors are obtained in a purilied state but admixed With an excess of steam or water vapor. If a di- A lute alkali solution is used in 4the phenol absorber, the hot gases may serve to remove added water from the solution, particularly when the solution is heated to ahigh temperature, so that the alkali phenolate solution "will become concentrated during the process. In order to separate the greaterv part of the Water vapor from the vurifed ammonia,the admixed ammonia an Water vapor escaping from the absorber are subjected to a condensing or dephlegmating treatment, giving 'a dilute ammoniacal solution, and a relatively' dry ammonia gas,

Which can then be passed tothe saturators or used for ,the production of aqua-ammonia.

For `the treatment of gas liquor which isv y rich in ammonia, the usual ammonia still can advantageously be supplemented by a preliminary countercurrent scrubber, which may be a separate scrubber or added sections on the 4still itself, in which the prei heated -gas liquor is caused to How countercurrent to the `ammonia gases driven olf from the still. By maintaining the liquor in this countercurrent scrubber at a sufficiently high. temperature, e. g. around 98 to 103 C.,

lseparation therefrom of phenolic compounds.

We' have found that phenol, in the presence of a large amount of ammonia forms or tends to form ammonium phenolate,which is more volatile than the phenol itself, and that the ammonium phenolate escapes With the ammonia if a sufficiently high temperature is maintained. If the temperature of the vapors or of the liquor With which they come in contact, is not suficiently'high, the phenolate is condensed Aand held back with the liquor instead. of escaping with the ammonia. Accordingly, in operating the. ammonia still itselffand in operating the countercurrent scrubber Where such a countercurrent scrubber is used, the temperature is maintained suiciently high, e. g. around 9S to 103 C., to insure that the phenolates will be driven off with the ammonia and prevented from recondensation and re-absorption by the liquor in or going to the still.

In the present process, the ammonia,togetzher with the. excess Water vapor and phenolic compounds, is taken o" from-the still at a hightemperature and subjected first to treatment to' separate the pheno-ls, as by absorption in caustic alkali to form alkali phenolates, and the ammonia is then passed, to a saturator or subjected to condensation or dephlegmation lto freeit from the greater part of its Water vapor, and ,then passed to the saturator. The condensed Water, together with its absorbed ammonia, may advantageously be returned to the countercurrent scrubber or even to the ammonia still4 itself to increase the ammonia content therein and to promote the removal of phenolate,

In the applicationof the invention to an aqua-ammonia s stem, the usual dephlegmator on top o the ammonia still should be removed, or used asl a heater to prevent undue cooling of the vapors, or as' a regulated cooler or condensermaintain'ed above 98 C. and the temperature of the liquor and vapors in the still should be maintained sufficiently high to insure the driving off-of the phenolic compounds with the ammonia. An absorber for the phenoliccompounds is provided, through which theA admixed ammonia, phenolic compounds, and moisture lare passed, and this absorber is advantaj geously maintained at a siiiliciently high temperature to prevent excessive condensation of water therein The ammoniacal vapors, thus freed from phenolic compounds, can

- thenbe subjected to a retluxing or dephlegmating operation for the condensation of the greater p art of the water vapors and to give a relatively dry ammonia gas. This ammonia gas can then be treated in the usual way for the production of aqua-ammonia. The aqueous ammoniacal liquor from thedephlegmator can be evaporated to recover the ammonia therefrom and this ammonia can be added to that used in the production of aqua-ammonia; or a part of this ammonia canbe returned kto the still itself to: increase the ammonia content of the gas liquor therein and to increase the removal of phenolic compounds, where the liquor is itself insuiicient in ammonia content for complete removal.

Instead of providing a separate phenol absorber for separating the phenolic compounds fromthe ammonia vapors, the vapors may be passed directly to a saturator.

In order to avoid excessive dilution of thements of apparatus, adapted for the practice 'p satnrator liquor, the ammoniacal vapors can gases the phenols can be recovered by pass-` be freed or kept free from excessive amounts of Water vapor, either by keeping the temperature of the vapors escaping from the still below-about 103 yC., or, where the vapors escape at a higher temperature, by passing them through a cooler where their temperature is reducedin order to separate water vapor .therefrom by condensation, andA the resulting ammonia .vapors may then be passed to`the saturator. The ammonium phenolate going into the saturatoravill be decomposed in the sulfuric acid bath and theV majority ofthe phenol setIl free, and will go out withthe inert gases, from which ing the gases through a phenol absorber such Aas an alkali washer. A ny phenols remaining in the saturator bath can be extracted by'distilling this bath ,after a certain concentration has been obtained and lthe vapors resulting Vfrom the distillation passed through a phenoly absorber suchas an alkali. washer for the recovery of thephe'nol as alkali phenolate.A

In the operation of an ammonia still,the temperature of theA liquor and of the vapors in the/top of the still may in some cases be maintained above 103 C.. such high tem-I peratures promoting the driving off of the aminoniumphen'olate with the ammonia.

At these ten'iperatures, however, an'increascd amount of water vapor is driven off with' the ammonia, and, ifthe vapors werel passed directly to a saturator, the water would'rdilute the saturator liquor to an objectionable degree. In such cases, the ammonia still is advantageously providedwith a reflux cooler or condenser or dephlegniator maintained ltemperature below 98 C.

at a sufiicicnt temperature to cool the gases to a temperature around 103 C. or somewhat lower (but above 98 C.) so that the excess water vapor will be condensed, and' so that the ammonia vapors can then be passed directly to the saturator without excesslve dilution of the saturator hquor.

-Where ammonia stills, such as those of aquawater vapor to the still, the temperature is so regulated that both the vapors and the liquor at the top of the still are above 98 C., and so as to prevent reabsorption of phenolic compounds in liquor maintained at a The invention will be described more in detail 1n connectlon-wlth the accompanying drawlng which illustrates different embodiof the process of the invention. While the different types of apparatus illustrated and described are all adapted for the practice or" the process of the invention in itsbroader aspect, the different apparatus differ from' each other in important respects, as will be `and returning as much as possible of the l hereinafter pointed out. So also, the process, as Will be understood, is 'not limited to any particular apparatus.

In the' accompanymg drawings, Fig. 1

.shows an ammonia still adapted for the practice ofthe process of the invention; Fig.' 2 illustrates, somewhat conventionally and diagrammatically, another arrangement of apparatus in the nature of a fiow sheet; Fig. 3 shows in elevation an aqua-amn'ionia apparatus, adapted for carrying out the invention; and Fig. 4 shows a modified apparatus.

The apparatus of Fig. 1 includes an ammonia still having heating means suiiicient to maintain'the temperature of the vapors and liquid at the top of the free ammonia, still suiiciently high, e.- g.,faround 98 to 103 Q. I

The still includes a prehcater 1,`heated by steamand having a gas liquor feed pipe 2, and a supplypipe 3 for, conveying the preheated liquor' to the top of the free ammonia still 6. A vent' pipe 3a is provided for the escape to the top of the still 6, of any vapors formed in the preheater. The still has the usual lime leg 8,-hav'ing steam heating coil 14. The fixed ammonia still 10 is connected with the lime leg through the connecting pipe 9 and the ammonia from the xed ammonia still escapes to the bottom of the free ammonia. still-through the erfor separating the phenolic compounds from the ammoniacal gases before they are further used. Another branch 7b having regulating valve therein, connects with the reflux condenser or cooler or dephlegmator 7, and the vapors from this reflux cooler escape through the pipe 7*? directly to the saturator,.or to a phenol-absorber and their to a saturator or ammonia absorber. A return pipe 7 conveys the condensate from the reflux cooler back to the free ammonia still. The reflux condenser or dephlegmator is arranged for indirect contact ofthe vapors with the cooling liquid. For example, the cooling liquid, such as water at a regulated temperature and in regulated amounts may fiow around tubes or pipes through which the vapors ascend, so that the vapors will be cooled, and so that the condensate therefrom will ow downwardly and collect in the bottom 'of the dephlegmator, and then return to the ammonia still.

In the operation of the apparatus of Fig. 1, the gas liquoris pre-heated in the preheater l to a .temperature of 98 C. or higher and is fed at-this temperature' to the top of the free ammonia still 6. In its passage downwardly throughthe free ammonia still,

the greater part or all of the free ammonia is driven ofi' and escapes through the outlet pipe 7. Inaddition, part or all of\the phel nolic compounds are removed with the ammonia, largely if not completely as ammonium phenolates. Vapors of ammonia, etc., set free in the pre-heater pass through the vent 3 or to the top of the ammonia still and are removed with the vapors therefrom. From the bottom of the-free ammonia still the liquor flows into the lime leg where it comes in contact with lime and where the lime reacts with the fixed ammonia compounds to set free the ammonia. The ammonia thus set free is driven ofi' in the fixed ammonia still 10 and the ammonia 4vapors passed into the bottom of the free ammonia still and upwardly therethrough,

assisting in the formation and the carrying olil of the phenols compounds as phenoiates. I/Vhere the gas liquor treated is rich yin ammonia, this ammonia may in itself be suffiipe has two branches, one,

may be supplied to the still, suflicient to effect the removal of an increased amount of the phenolic compounds or even to effect substantially complete removal thereof.

It will be noted that the free ammonia still of Fig. 1 is shown broken away at an intermediate point to indicate an indefinite height of the still. The still may be of the usual height and with the usual number of sections. In order, however,lto provide for additional contactof the ammonia vapors with the pre-heated liquor, the still may advantageously have added sections, in addition to those of the ordinary still, and these will provide an increased scrubbing action 'of the ammonia vapors rising upwardly through the still through the scrubbing sections and the pre-heated liquor flowing downwardly through these sections and through the free ammonia still. By increasing this counter-current flow and scrubbing action, and by maintaining the temperature of both the liquor and the gases and vapors above 98 C., a more complete driving ofi' and removal of phenolic compounds .with the ammonia can be obtained.

Where the temperature of the vapors escaping from the top of the free ammonia still is not too hi more, they may 2loe passed directly to a saturator or to a phenol absorber and then to a saturator. Where the vapors are at a Vhigher temperature and contain an vincreased amount of water vapor, they may advanf tageously be subjected to a regulated condensing or ref'luxing operation in the reflux condenser or dephlegmator 7g and the temperature cooled to 103 C. or lower with return of the excess water vapor to the still inl a condensed form. The vapors can be cooled to a temperature below 103 C. but should not be cooled to a temperature below 98 C., and the liquor in thev bottom of the dephlegmator, and returning to the still, should not be cooled below 98 C. The provision of a dephlegmator, as illustrated in Fig. 1, enables the temperature of the escaping vapors to be 'regulated and controlled, to remove excess water vapor therefrom, while nevertheless permitting escape of phenolic compounds with the i ammonia', while the provision of a direct connection 7 permits the vapors from thel still to be passed 0h, e. g. is at 103 C. or

directly to a saturator or to a phenol absorber without additional dephlegmation, in

- which case the temperature of the liquor and vapors in the top of the free ammonia still l itself, or in the top of the added scrubbing section superimposed thereon, will determine the moisture content ef the escaping vapors. The temperature of both the liquor and the vapors at the outlet from the still should be sufliciently high to prevent reabsorptlon of phenolic compounds in the liquor, i. e. it

should be at 98 C. or higher,

In the apparatus of Fig. 2 the pre-heater and the free and fixed ammonia stills are given the same reference characters as in Fig. 1, and the still is operated in a similar way, except for the modifications described below.

In Fig. 2 a separate countercurrent scrubber is provided between the gas .liquor preheater andthe free ammonia still and the pre-heated liquor is subjected to the total vapors coming from the ammonia still. That is, the gas liquor from the pre-heater 1 passes through the pipe 3` to the top of the counter-current scrubber 4 and passes downlvvardly therethrough, the resulting liquor then passing through the pipe 3a to the top of the free ammonia still. From the top of the free ammonia still the vapors of ammonia, etc., pass through the pipe 7 tothe bottom of the countercurrent scrubber 4 and upwardly therethrough countercurrent to the dovvnflowing pre-heated liquor. The am-` moniacal vapors from the top of the countercurrent scrubber 4 may pass through the pipe 18 directly to a saturator or through the branch pipe 19 to a phenol absorber, Such as analkali Washer 20. In this absorber they are brought into intimate con-A tact with an absorbent, e. g. a caustic alkali 4solution which will decompose the ammonium phenolate and form alkali phenolate. The remaining ammoniacal vapors `then pass through the pipe 21 to the condenser or dephlegmator 22 in which they are subjected to cooling and aconsiderable part of the Water vapor separated out as ammoniacal liquor whichv returns through the pipe 23 to the bottom of the countercurrent scrubber 4. AThe purified and dried a1n monia gas then passes through the pipe 2,4 and the pipe 18 to the saturator or to other place of treatment or use. The alkali phenolate solution collecting in the Washer 2O can be drawnoi through the outlet pipe 27 having Aregulating valve 28 therein. By closing the valves in the pipes 19 and 24, the vapors can be passed directly to a saturator. In Fig. 2 it will beynoted that a phenol absorberv is arranged so that the vapors passing from the free ammonia still 6 to the scrubber 4 may be passed through the absorber, or

. by-passed directly from the still to the scrubber. The connecting pipe 5 has a direct branch 5, With valve therein, by means of which the ammonia ,vapors from the still can be passed directly to the scrubber. It also has a branch- 5b with valve therein, by means of which the vapors can pass to the phenol absorber 5d, for the separation of phenolic compounds-therein, after which the purilied ammonia gases pass through the branch pipe 5c to the scrubber. This phenol absorber may contain an alkali solution to break up the ammonium phenolate and form alkali phenolate which may be removed from time 2 the gas liquor is first pre-heated to a temperature of 98 C. or`higher in the'pre- ,heater 1 and then passes into the scrubber 4 where its temperature is maintained at 98 C. or higher. In this scrubber it is subjected to the scrubbing action of the vapors escaping from the top of the free ammonia still through the pipe 7. These vapors may include ammonia together with ammonium phenolate or they may have the phenolate removed therefrom by the absorber 5d. The maintenance of the temperature of the scrubber at 98 C. yor higher insures that any ammonium phenolate will not be condensed and held in the scrubber but will be driven off to a large extent if not completely with the ammonia escaping through the pipe 18. The gas liquor thus freed from a considerable4 part of itsl ammonia and phenolate enters the top of the free ammonia still where the usual distilling operation takes place, the greater part or all of the remaining free ammonia being set tree in the free ammonia still and the fixed am-A monia being then set free by the action of lime and distilled in the fixed ammonia still. The ammonia set free in the fixed ammonia still 'passes upwardly through the free ammonia still and serves to assist in carrying away any remaining phenolic com- -pounds which the liquor contains at this place. By providing a sutlicient amount of vcomplete removal of phenolic compounds so that `the liquor lthat comes in contact with the linie inthe lime leg will contain no phenolic compounds. `Inasmuch as such compounds if present in the liquor coming in contact with the lime will combine with the lime to form calcium phenolate and will beheld and prevented from volatilizing, it is important to effect removal more or less completely of the phenolic compounds from the liquor before it comes in contact with the lime. y

By operating fthe phenol absorbers at a high temperature, for example, by using a strong caustic sodaA solution and heating it to a high temperature, absorption or condensation of Water vapor is prevented, and a strong solution of sodium phenolate can be obtained. In the case of the phenol absorber 5d, this maintenance of the absorbent solution at a -high temperature prevents cooling of the ammonia gases entering the bottom of the scrubber 4. In the case of the phenol absorber '20, the hot ammonia and admixed water vapor pass to the dephlegmator or condenser 22 where the vapors are cooled and the ammonia is separated from the greater part of its admixed lill) water vapor. The condensed watertogether with absorbed and condensed ammonia pass back to the countercurrent scrubber as already pointed out. In addition a further amount of ammonia -gas can if desired be returned either to the countercurrent scrub-- ber or to the free ammonia still to increase fthe amount of phenols driven off, and to effect substantially complete removal of phenols from the liquor. In the apparatus illustrated in Fig. 2 the lime leg is heated by the steam coil 14 having regulating valve 17 therein and the fixed ammonia still by the steam coil 15 having regulating valve 16. An outlet pipe for the waste liquor from the fixed ammonia still is indicated at 12 having valve 13 therein.

IVhen the alkali solution in the washers becomes charged with phenols, they may be drawn off and replenished, and the phenol can be 4recovered therefrom in any suitable manner, as for example, by acidifying 'the solution and distilling off the phenol, gr the alkali phenolate may b'e utilized for other purposes.

In the apparatus of Fig. 2, the countercurrent scrubber 4 may be of any suitable construction which will permit effective countercurrent contact betweenthe gases and liquor. current extension of the free ammonia still itself, similar to the added sections on top of the free ammonia still of Fig. 1. The provision of a separate scrubber, however, makes possible the countercurrent treatment of the preheated gas liquor before. it reaches the usual free ammonia still, as well as the freeing of the vapors from phenol before they enter the separatescrubber.

Fig. 3 illustrates a modified apparatus for producing aqua ammonia and at the same time recovering a large percentage or all of the phenol from the. gas liquor.

Gas liquor flows from the feed tank 102 into the scrubber 104 and from thence into the preheater 101 where the liquor is heated to a temperature approximately 98 C. to

99 C. The het liquor then passes through the pipe 103 and 105 into the flee. ammonia or volatile still 106 or, if desired, the valve '112, may be closed and the hot liquor pumped under positive pressure by the liquor pump- 113. The free ammonia still 106 is maintained at a temperature such that both the liquor and vapors are at or above 98o C. Most of the free ammonia and a large percentage of the phenol as ammonium phenolate is volatilized in the still 106, the liquor passing down into the liming leg 108 while still containing a small percentage of phenol, if the phenol is not completely removed. The lime in the lime leg sets free In effect, it forms a counter-- the ammonia set free by the lime is volatilized and is returned to the volatile still 106 through the pipe 111. An automatic overflow' 115, controlled by valves,114 and 116, provides for the overflow of liquorI from the fixed ammonia still.

The vapors containing ammonia and phenolate from the free ammonia still pass through the pipe 107 into the alkaliwasher where the ammonium phenolate is decomposed and the phenol removed from the vapors in the form of alkali phenolate, which is withdrawn from time to time and the phenol recovered above described. The phenol-free vapors from the alkali washer pass through pipe 121- into the ammonia condcnsei- 122 where most of the water is condensed out and flows into the evaporators 118 through pipe 117. The ammonia from the condenser passes into the water washer 123 through the pipe 124 and lthe ammonia dissolved in the condensate is led from the evaporators 118 into the Water washer through pipe 125. The' ammonia is thenwashed as usual with oil in the oil washer 126, with the monitor 127, and is filtered in the charcoal filter 128 and bone black filter 129 'and finally passed into the absorbers 130 and 131, Where it is absorbed in distilled water supplied from the tank 132.

It will be seen that the apparatus of Fig. 3 differs from the usual aqua-ammonia plant in that the dephlegmator -is removed fromthe top of the ammonia, still and an alkali washer is introduced between the top of the ammonia still and the dephlegmator or condenser. This permits the free ammonia still to be operated at a higher temperature and Without refluxing and return of Water and -phenolate to 'the still, and permits the am- A monia with admixed Water vapor and phenolthe combined ammonia and the liquor passes ate to pass over to the alkali Washer where the phenolate is decomposed and the phenol absorbed as alkali phenolate before the ammonia is subjected to condensation to remove the admixed water vapor therefrom. This removal of the condensers to a distance from the still and the introductionl of an alkali washer between the still and condenser, together With the operation of the still itself at a sufficiently high temperature permits the phenolate to be removed from the still with the ammonia and to be recovered before the ammonia is subject-ed to condensation to remove the water vapor therefrom. By op erating the alkali Washer at a high temperature, the Water vapor is prevented from condensing in the washer andI from diluting the alkali solution.

lVhile theY apparatus illustrated in Fig. 3 has the usual dephlegn'iator removed from .thcl top of the ammonia still. the dephlegmator can nevertheless be used in the manner described in connection with Fig. l. In-

lli)

lil() amar/'ee Y stead, however, of cooling the ammonia va' considerably higher than 98 C. can be maintained in the free ammonia still, and the dephlegmator can be relied upon to cool the vapors down to a temperature such that excessive amounts of water vapor are removed, but ammonium pheuolate nevertheles pci'- mitted to pass ofi' with the ammonia.

The apparatus of Fig. 4 is a modified apparatus in which the preheated gas liquor is brought into Contact with the total ammonia evolved from-the gas liquor without recycling of ammonia vapor'. ln this figure, the same reference numerals are used as in Figs. 1 and 2 for corresponding parts of the apparatus. with the suffix?) appended thereto in certain cases.

In this apparatus, the gas liquor from the preheater charge passes at a temperature of 98 C. or higher to the top of the free ammonia still 6b and flows downwardly therethrough. From the bottom of the free ammonia still the liquor flows through the pipe 3 to the top of the countercurrent v scrubber 4, in which the liquor is maintained at a temperature of 98 C.l or higher. The liquor fiows downwardly7 through the scrubber and leaves the base of the scrubber through the pipe 3d, through which it is 4pumped by the pump 3, to the lime leg 8v of theammonia still. and then through the regular fixed still. The ammoniacal vapor from the :tree ammo-nia. still passes off through the pipe 5* to the bottom of the countercurrent scrubber 4 and passes upwardly therethrough couutercurrent to the liquor.

The general arrangement of the apparatus of Fig. 4 is similar lto that of Fig. 2 except for the different arrangement of the counter current scrubberwith reference to the ammonia still. `In the apparatus of Fig. 2, the preheated liquor first enters the scrubber and then passes to the free ammonia still; while in the apparatus of Fig. 4, the liquor is first preheated and passes to the free ammonia still and subsequently to a countercurrent scrubbing before it enters the lime lleg. In the apparatus of Fig. 4, the ammonia set free in the fixed ammonia still passes upwardly through the free ammonia still and the ammoniacal vapors are taken off from the top of the free ammonia still at a temperature sufficiently highto insure the carrying oli'l of phenolic compounds with r the ammonia, i. e., a temperature of 98 C; lor

higher. The total amount 'of ammonia is then caused to pass countercurrent to the liquor in the scrubber 4.

A phenol absorber 5d may be provided in Fig. 4 similar 4to the phenol absorber 5'd in Fig. 2. By proper manipulation of the valves in the pipe 5, 5b and 5, the phenol absorber can be omitted or included as desired. When the' gases from the free ammonia still are passed through the phenol absorber (containing, for example, a solutioncf caustic soda), the ammonium phenolate will be decomposed, the phenol will be combined with the caustic soda as sodium phcnolatc, and the ammonia set free will be carried along with the other ammonia into the countercurrent scrubber. By purifying the ammonia in this way, the liquor in the scrubber will he subjected to the countercurrent action of the ammonia and, by maintaining the scrubber at a temperaure of 98 C. or higher, further opportunity is presented for the ammonia to combine with and carry away the phenolic compounds as phenolate. The phenolic compounds carried over from the scrubber through the line'lS can be treated, for example, as described in connection with Fig. 2 ab'e.- Where the amount of phenolic compounds in the liquor is small with reference to the ammonia content, the phenol absorber 5d may be omitted and the ammonia may be sufiicient in such case to effectA substantially complete removal ot' the phenol. lVith the, phenol absorber available for use where desired, and with the arrangement of Fig. 4, substantially complete removal Vof phenolic compounds can be effected, particularly where the gas liquor is high in ammonia; and this can be effected without recycling of am- 1 monia. c

In'the apparatus of Fig. 3, as well as m the apparatus of Figs. l, 2 or 4, wher-e the normal ammonia content cf the gas liquor is low or is insuiiicieut to effect complete removal of phenolic compounds as ammonium phenolate', additional ammonia may be supplied to the still to increase the phenoli:l recovery. Even without the addition of ammonia, however,'an important recovery of phenols can be obtained, particularly from gas liquor which is itself rich in ammonia. lVhere the ammonia content in the still is to be increased, the ammonia may advantageously be that which is recovered from the vprocess itself, after purification from admixed phenolate. lVe do not, however, claim herein the cyclic process in which the ammonia is so purified and returned to the still, inasmuch as suclrcyclic )recess and apparatus forms the subject o a separate application. 7With such cyclic operation, it is readily possible to recycle suflicient ammonia to insure that substantialiy all of the phenolic compounds will be driven oli' so that they may be` recovered, and so that hul pounds.

the waste liquor from the still will be4 freed from objectionable l. phenolic constituents. Even without such vrecycling of ammonia, however, and particularly'if the gas liquory is itself rich in ammonia, -the process of the 'presentinvention permits. the recovery of.

important amounts of phenol from the gas liquor which are normally lost and not recovered. The present vprocess,.-according1y provides for a new source 'of recovery of phenols, and,to` the extent that the'phenols are lvrecove redthe waste liquor is freed' from objectionable phenolic constituents. f

We claimzl 1.' The process of treating gas liquor containing phenolic impurities which comprises subjecting the liquor Ato distillation for kthe recovery lof ammonia therefrom, the temperature of the liquor and vapors at -th'e outlet ofthe ammonia from vthe still being about 98 C. or highertodrive ofi' ammonium phenolate with the ammQpa.

2. The process of treating gas liquor containing phenolic impurities which comprises subjecting-the liquorto distillation'for the recovery of ammonia therefrom, the temperature of the liquor and vapors being, maintained aroundl 98.9 C. or higher, whereby phenol isremoved with the. ammonia. as

phcnolate.l

3f The process of treatin'ggas liquor containing phenolic -impurities which. comprises subjecting the same toA distillation in a free ammonia vstill for the removal o f free amr monia therefrom, then setting free the fixed ammonia an passing it through the free ammonia sti and -maintaining the temperature of the liquor and va ors' at the top of the free ammoniastill at a ut 98 C. or higher,whereby phenol is driven 06. from the free ammonia still as phenolate with the ammonia.. v

4..' 1he process" of treating gas liquor.containing phenolic inipuritieswhich comprises subjecting the same to distillation at a temperature of around 98 C. or higher to remove recovering the phenol and ammonia.-

Tlieprocess of treating gas liquor containing phenolic impuritiesv which comprises pre-heating the liquor, introducing the preheated liquor into an ammonia still, the v liquor in theupper portion of which is maintained at a temperature of about 98 to 103 C., and passing the vapors from the ainmonia still through a phenol absorber to separate phenolic compounds from the ainv monia.

The process' of treating gas liquor containing phenolic impurities which comprises pre-heating the liquor, introducing the precated liquor into anl ammonia still, the liquor in the upper portion of whichis maintained at a temperature around 98 C. or higher to drive ofi' phenolic compounds with the ammonia, passing the admixed vapors 'through a phenol absorbent, subset quently cooling the ammonia vapors to sepa# rate water` vapor therefrom, and returning the ammoniacal liquor thus separated to the Vliquor from which the ammonia is being driven olf.

8. The process'of treating gas liquorconf taining phenolic impurities which comprises pre-heating the same, introducing the vpreheated liquor into an ammonia still, the

liquor in the upper portion of which isA mainctained'at temperature around 98 C. or higher to drive olf phenolic compounds lwith the ammonia, and conveying any vaporsset free in the pre-heater to the am' monia still for admixture with the-vapors escaping therefrom.

9. The processof treating gas liquor containing phenolic impurities which comprises preheating the liquor, introducing the preheated liquor into an ammonia still, and subjecting the pre-heated liquor before entering the still to tlie""`scrubbing action of the ammonia given oli from the still, the temperatureof the preheated liquor during such scrubbing opera-tion being around- 98 C. or higher to drive off with the ammonia.

10, The process of treating gas liquor phenolic compounds vcontaining phenolic impurities which comlll) prises :pre-heating the liquor passing the .preh-eated liquor through' a ,scrubber. and

thenl introducing ityintov an 'ammonia' still, thefliqii'or in the upper-portion of which is maintained .at a temperature around 98 C.

or higher to drive olf phenolic compounds with the ammonia, and passing the ammonia and phenolicl compounds so driven olf throiigh'thescrubber countercuri'ent to the pre-heated liquor, the temperature of the liquor in the scrubber being maintained suficiently high to remove phenolic compounds with the ammonia.

11. The process of treating gas liquor containing phenolic impurities v vhichv comprises pre-heating the same,'p'a`s sing the pre heated liquor-through a scrubber andthen to an ammonia still, passing thev ammonia vapors from the still through lthe scrubber countercurrent to the pre-'heated liquor, the

and subsequently monia Water vapor temperature of the liquor'in the` scrubber land in the still being around 98"v C.V or

higher to drive off phenolic compounds with the ammonia',- passing the admixed ammonia and phenolic compounds through a scrubber to remove the phenolic compounds, cooling the resulting ammonia to separate water therefrom and returning the ammoniacal water so separated to the scrubber.

12. The improvement in the production of aqua-ammonia from gas liquor containing containing. phenolic 'impurities which comprises pre-heating the liquor, introducing the pre-heated liquor into an ammonia still, the temperature of the liquor in the upper portion of Which is maintained' around 98 C. or higher to 'drive oli' phenolic compounds with the ammonia, passing the resulting admixed vapors through a'n alkali washer maintained `at a suiiiciently high temperature to prevent condensation ofv water vapor,

cooling the admixedl amto separate water from the ammonia.

14.' The process of treating gas liquor containing phenolic impurities which comprises pre-heatlng the liquor to a temperature of 98 C. or higher, introducing the pre-heated liquor into an ammonia still and subjecting the same to distillation therein with maintenance of the temperature of the liquor around 98 C. or higher to drive off ammonium phenolate with the ammonia, and subjecting the escaping ammonical vapors to a regulated refiuxing or dephlegmating treatment at a temperature suiiiciently high to insure the driving ofi' of ammonium phenolate with the ammonia while condensing the excess water vapor.

15. The process of treating gas liquor containing phenolic impurities which comprises preheating the liquor, passing the preheated liquor through a scrubberland then introducing it into an ammonia still, the liquor in the upper portion of which is maintained at a temperature around 98 C. or higher to drive off phenolic compounds with the ammonia, passing the ammonia and phenolic compounds so driven off through a phenol absorber to separate phenolic compounds from the ammonia, and passing the resulting purified ammonia through the scrubber countercurrent to the preheated liquor, the temperature of the liquor in the scrubber being maintained suiiciently high to remove phenolic compounds therefrom With the ammonia.

16. The process of treating gas liquor which comprises preheating the liquor, passing the preheated liquor through a free ammonia still with resulting evolution of ammonia, passing the liquor from the free ammonia still through a countercurrent scrubner, countercurrent to the ammoniacal vapors given ofi from the free ammonia still, subsequently passing the liquor to the fixed ammonia still with resulting setting free of ammonia therefrom and passing the ammonia set free inthe fixed ammonia still to the free ammonia still.

In testimony whereof we aiiix our signature".

a LE RoY WILBUR HEFFNER.

WM. Tinnr. 

